(1) Field of the Invention
The present invention relates to a negative temperature coefficient thermistor for use mainly in measuring temperature of compensating for thermal characteristics of other electronic elements or circuits and to a method of producing the same.
(2) Description of the Prior Art
Negative temperature coefficient thermistors are known, and reference may be made, for example, to Japanese Patent Publication No. 52-7535. The document discloses a thermistor having such a construction that a thermistor element produced through sintering a powdered material of ceramic in the form of a chip is sandwiched by a pair of electrodes and enclosed in an envelope made of glass. In this regard, the glass envelope operates to secure or stabilize the thermal and chemical properties of the thermistor element when the thermistor is used for measuring temperature.
A thermistor of the above type, however, has a drawback of requiring relatively complicated production processes because it necessitates the formation of the glass envelope other than that of the thermistor element. In addition, the thermistor element necessitates lead wires to be connected to external devices, which means that it is quite difficult to directly mount the thermistor onto a printed circuit board.
Furthermore, the glass envelope for enclosing the thermistor element has its melting point at about 400.degree. C., therefore, the thermistor is not usable for measuring a temperature at about 1000.degree. C.